The flat panel display devices possess many merits of thin frame, power saving, no radiation, etc. and have been widely used. The present flat panel display devices at present mainly comprise the Liquid Crystal Display (LCD) and the Organic Light Emitting Display (OLED).
The thin film transistor (TFT) is an important component of the flat panel display device. The TFTs can be formed on a glass substrate and a plastic substrate and generally employed as switch elements and driving elements utilized such as flat panel displays, LCDs, OLEDs and et cetera.
The oxide semiconductor TFT technology is the most popular skill at present. Because the oxide semiconductor has higher electron mobility and in comparison with the Low Temperature Poly-silicon (LTPS), the oxide semiconductor manufacture process is simpler and possesses higher compatibility with the amorphous silicon process, it can be applicable to the skill fields of LCD, OLED flat panel display devices and etc. Because it fits the new generation production lines and has possible applications for displays with Large, Middle and Small sizes. The oxide semiconductor has the great opportunity of application development.
At present, in the active array flat panel display device, the TFT substrate generally utilizes the single-gate oxide semiconductor thin film transistor (Single-Gate TFT). The dual gate oxide semiconductor thin film transistor (Dual-Gate) possesses better performance than the single gate oxide semiconductor thin film transistor, For example, the electron mobility is higher, and the current of activation state is larger, and the subthreshold swing is smaller, and the stability and the uniformity of the threshold voltage are better, and the gate voltage bias and the light stability are better.
In the manufacture of the LCD, the manufacture of the color filter can be accomplished in the process of the TFT array substrate, i.e. utilizing the COA (Color Filter On Array) technology. As shown in FIG. 1, the a structure of a dual gate oxide semiconductor TFT substrate applicable for the LCD utilizing the COA technology according to prior art comprises a substrate 100, a bottom gate 200 on the substrate 100, a gate isolation layer 300 on the substrate 100 and the bottom gate 200, an oxide semiconductor layer 400 on the gate isolation layer 300 above the bottom gate 200, an etching stopper layer 500 on the oxide semiconductor layer 400 and the gate isolation layer 300, a source/a drain 600 on the etching stopper layer 500, a passivation layer 700 on the source/the drain 600 and the etching stopper layer 500, a top gate 800 on the passivation layer 700 above the source/the drain 600, red/green/blue color resist layers 900 on the top gate 800 and the passivation layer 700, a first flat layer 910 on the red/green/blue color resist layers 900 and the passivation layer 700 and an ITO pixel electrode 1100 on the first flat layer 910.
The etching stopper layer 500 is formed with a first via hole 510 and a second via hole 520 correspondingly above the oxide semiconductor layer 400, and the source/the drain 600 respectively contact with the oxide semiconductor layer 400 through the first via hole 510 and the second via hole 520; the passivation layer 700 and the first flat layer 910 is formed with a third via hole 530 correspondingly above the source/the drain 600, and the ITO pixel electrode 1100 contacts with the source/the drain 600 through the third via hole 530.
As manufacturing the dual gate oxide semiconductor TFT substrate, except the substrate 100 and the gate isolation layer 300, every other structure layer is implemented with the pattern process with one photo process. Thus, the number of the required photo processes is more. Obviously, the structure of the dual gate oxide semiconductor TFT substrate applicable for the LCD utilizing the COA technology is more complicated. The procedure of the manufacture method is longer, and the production efficiency is lower, and the production cost is higher.